102 BFRTIIA'S- VISIT TO HER 



hill had quite escaped ; and as he thought 

 .vajiiiy.7-rt.vusl be Warmel- than hills, he begged of 

 my uncle to explain the cause. 



" Valleys," he was answered, " are more 

 sheltered from the wind ; and the air in them is 

 undoubtedly hotter in the day time than that on 

 exposed high grounds. But in autumn, when 

 the nights become cold, and slight frosts occur 

 on the sides of the hills, the air that is cooled 

 there being heavier than warm air, sinks down 

 into the lower grounds, displaces the warm 

 air, which rises, and accumulates in the bottom 

 of the valley. 



"There is another reason why, on clear 

 nights at least, the cold is more severe in low 

 confined places that are sheltered from the 

 wind. The radiation of heat into the sky, 

 which I lately explained to you, reduces their 

 temperature below that of the air, except what 

 is in immediate contact with them ; and there 

 being no wind, there can be no circulation of 

 the warmer air to replace the heat they have 

 lost." 



lltJi. Hamlet was mentioned yesterday after 

 dinner; a great deal was said about it, and 

 many different opinions were expressed. At 

 last, to my great vexation, my uncle observed 

 that I took no part in the conversation. 



" Come, my little Bertha, we must have yeur 



